JP7547970B2 - Vehicle control device - Google Patents

Description

This disclosure relates to a control device for a vehicle that includes an internal combustion engine, a transmission that transmits power from the internal combustion engine to drive wheels, and an air conditioning device that uses the internal combustion engine as a heat source to condition the air inside the vehicle cabin.

Conventionally, there is known a control device for an engine (internal combustion engine) mounted on a vehicle that, when it is determined that a fuel cut request has been made to the engine, determines whether a heating request has been made to a heater that uses the engine's coolant as a heat source (see, for example, Patent Document 1). This control device cuts fuel to the engine when a fuel cut request has been made but a heating request has not been made, and executes normal fuel injection control when a fuel cut request has been made and a heating request has been made. As a result, when a heating request has been made, even if a fuel cut is requested to improve the fuel efficiency of the engine, the fuel cut is not executed, and the heating performance of the heater can be ensured by continuing the supply (combustion) of fuel.

JP 2009-167856 A

However, in a vehicle including the above-mentioned control device, if fuel cut is prohibited in response to a heating request while driving downhill, for example, the deterioration of the heater's heating performance is suppressed, but sufficient deceleration cannot be ensured when the driver releases the accelerator pedal, which may result in a deterioration in the drivability of the vehicle.

Therefore, the primary objective of this disclosure is to further improve the drivability of a vehicle while suppressing the deterioration of the heating performance of the air conditioning system.

The vehicle control device disclosed herein includes an internal combustion engine, a transmission that transmits power from the internal combustion engine to drive wheels, and an air conditioning device that uses the internal combustion engine as a heat source to condition the interior of the vehicle, and in which fuel cut is performed by the internal combustion engine in response to the establishment of a fuel cut execution condition, including the release of the accelerator pedal. The vehicle control device includes a fuel cut prohibition request unit that requests the prohibition of the fuel cut when the temperature of the internal combustion engine is equal to or lower than a predetermined fuel cut prohibition request temperature, and a fuel cut permission/prohibition determination unit that, in response to the request for prohibition of the fuel cut by the fuel cut prohibition request unit, obtains a lower limit vehicle speed that allows the prohibition of the fuel cut corresponding to the current gear ratio of the transmission, and prohibits the fuel cut when the vehicle speed is equal to or higher than the lower limit vehicle speed, and permits the fuel cut when the vehicle speed is less than the lower limit vehicle speed.

In the control device disclosed herein, the fuel cut prohibition request unit requests the prohibition of fuel cut in order to ensure the heating performance of the air conditioner when the temperature of the internal combustion engine is equal to or lower than a predetermined fuel cut prohibition request temperature. In addition, the fuel cut permission/denial determination unit acquires a lower limit vehicle speed that permits the prohibition of fuel cut corresponding to the current gear ratio of the transmission in response to the request for prohibition of fuel cut by the fuel cut prohibition request unit. Then, the fuel cut permission/denial determination unit prohibits fuel cut when the vehicle speed is equal to or higher than the lower limit vehicle speed, and permits fuel cut when the vehicle speed is lower than the lower limit vehicle speed. As a result, when the prohibition of fuel cut is requested by the fuel cut prohibition request unit and the vehicle speed is equal to or higher than the lower limit vehicle speed, fuel cut is not executed even if the fuel cut execution condition is established, so that the heating performance of the air conditioner can be well ensured. In addition, in this case, since the vehicle speed of the vehicle is relatively high, it is possible to ensure sufficient deceleration in response to the release of the accelerator pedal by changing the gear ratio of the transmission to the deceleration side. In contrast, when the fuel cut prohibition request unit requests the prohibition of fuel cut and the vehicle speed is below the lower limit vehicle speed, fuel cut is executed in response to the establishment of the fuel cut execution condition. Although this may result in a slight decrease in the heating performance of the air conditioning device, it is possible to ensure sufficient deceleration by fuel cut in response to the release of the accelerator pedal. As a result, according to the vehicle control device disclosed herein, it is possible to further improve the drivability of the vehicle while suppressing the decrease in the heating performance of the air conditioning device.

The lower limit vehicle speed may be determined in advance for each gear ratio of the transmission as the lower limit value of the vehicle speed that allows the required deceleration when the accelerator pedal is released to be ensured by changing the gear ratio, and may be set higher as the gear ratio becomes smaller. This makes it possible to further improve the drivability of the vehicle while appropriately ensuring the region in which prohibiting fuel cut is permitted and suppressing a decrease in the heating performance of the air conditioning device.

Furthermore, the fuel cut prohibition request temperature may be set higher as the outside air temperature decreases. This makes it possible to appropriately request the prohibition of fuel cut to ensure the heating performance of the air conditioning device.

The fuel cut permission/prohibition determination unit may permit fuel cut before the internal combustion engine has finished warming up, regardless of a request for fuel cut prohibition by the fuel cut prohibition request unit, and may compare the vehicle speed with the lower limit vehicle speed in response to a request for fuel cut prohibition by the fuel cut prohibition request unit after the internal combustion engine has finished warming up. This makes it possible to effectively prevent vehicle occupants from feeling a decrease in the heating performance of the air conditioning device.

1 is a schematic configuration diagram showing a vehicle including a control device according to the present disclosure. FIG. 4 is an explanatory diagram illustrating a map for setting a fuel cut prohibition request temperature. 4 is a flowchart illustrating a fuel cut permission/refusal routine executed in the vehicle of FIG. 1; FIG. 4 is an explanatory diagram illustrating a map for setting a warm-up determination water temperature. FIG. 11 is an explanatory diagram illustrating a map for setting a fuel cut prohibition permission lower limit vehicle speed.

Next, the form for implementing the invention of this disclosure will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a vehicle 1 including a control device according to the present disclosure. The vehicle 1 shown in the figure includes an engine (internal combustion engine) 10 including a plurality of combustion chambers (cylinders), a power transmission device 20 that transmits power from the engine 10 to drive wheels DW, and an air conditioning device 30 that conditions the air inside the vehicle cabin. The engine 10 is controlled by an engine electronic control device (hereinafter referred to as the "engine ECU") 100. The power transmission device 20 is controlled by a transmission electronic control device (hereinafter referred to as the "TMECU") 200 that exchanges information with the engine ECU 100. Furthermore, the air conditioning device 30 is controlled by an air conditioning electronic control device (hereinafter referred to as the "air conditioning ECU") 300. The vehicle 1 may be a rear-wheel drive vehicle as shown in the figure, a front-wheel drive vehicle, or a four-wheel drive vehicle.

The engine 10 is a gasoline engine that burns a mixture of gasoline (hydrocarbon fuel) and air injected from an injector (not shown) in multiple combustion chambers and converts the reciprocating motion of the pistons caused by the combustion of the mixture into the rotational motion of the crankshaft 11. However, the engine 10 may also be a diesel engine or an LPG engine. The engine ECU 100 that controls the engine 10 includes a microcomputer having a CPU, ROM, RAM, input/output interface, etc. (not shown), various drive circuits, various logic ICs, etc., and executes intake air amount control, fuel injection control, ignition timing control, etc. of the engine 10. When performing various controls, the engine ECU 100 acquires detection values from the crank angle sensor, air flow meter, intake pressure sensor, air-fuel ratio sensor, etc. (all not shown), the temperature of the engine 10 coolant (hereinafter referred to as "coolant temperature") Tw detected by the water temperature sensor 101, the outside air temperature Ta detected by the outside air temperature sensor 102, the vehicle speed (current vehicle speed) V detected by the vehicle speed sensor 103, the accelerator opening Acc (amount of depression of the accelerator pedal 105) detected by the accelerator pedal position sensor 104, etc.

In addition, in this embodiment, when fuel cut execution conditions are met, including, for example, that the engine 10 rotation speed is equal to or higher than a predetermined rotation speed, that the shift lever of the transmission 25 is in a forward driving range, and that the driver releases the accelerator pedal 105, the engine ECU 100 controls the multiple injectors to stop the supply of fuel to all combustion chambers. When the fuel supply to each combustion chamber is stopped, i.e., a fuel cut is executed, friction torque from the engine 10 is transmitted to the drive wheels DW via the transmission 25, etc., and the vehicle 1 can be decelerated by so-called engine braking, or fuel efficiency can be improved by coasting the vehicle 1.

The power transmission device 20 includes a torque converter (fluid transmission device) 21 with a torque amplification function, a lock-up clutch 22, a damper mechanism 23, a mechanical oil pump 24, a transmission 25, a hydraulic control device 28 that adjusts the pressure of the hydraulic oil, and the like. The torque converter 21 includes a pump impeller connected to the crankshaft 11 of the engine 10 via the front cover (input member), a turbine runner connected to the input shaft 26 of the transmission 25, and a stator that amplifies the torque by rectifying the flow of hydraulic oil from the turbine runner to the pump impeller. The lock-up clutch 22 is a multi-plate or single-plate friction hydraulic clutch that connects the front cover and the input shaft 26 of the transmission 25 via the damper mechanism 23 and releases the connection between them.

The transmission 25 is a stepped (multi-stage) transmission, for example, of 6-10 speed type (8 speed type in this embodiment) including an input shaft 26, an output shaft 27, multiple planetary gears, and multiple clutches and brakes (engagement elements for shifting). However, the transmission 25 may be a dual clutch transmission. The transmission 25 shifts the power transmitted from the crankshaft 11 of the engine 10 to the input shaft 26 via either the torque converter 21 or the lock-up clutch 22 into multiple stages and outputs it from the output shaft 27 to the drive wheels DW via the differential gear 29 and the drive shaft DS. The hydraulic control device 28 also includes a valve body in which multiple oil passages are formed, multiple regulator valves, multiple linear solenoid valves, etc.

The TMECU 200 that controls the power transmission device 20 includes a microcomputer having a CPU, ROM, RAM, input/output interfaces, etc. (not shown), various drive circuits, various logic ICs, etc., and controls the hydraulic control device 28 to adjust the hydraulic pressure from the mechanical oil pump 24 and supply it to the torque converter 21, the lock-up clutch 22, the clutch and brake of the transmission 25, etc. In addition, when upshifting or downshifting the gears of the transmission 25, the TMECU 200 obtains a target gear corresponding to the accelerator opening Acc and the vehicle speed V from a previously created shift line diagram, and controls the hydraulic control device 28 so that the obtained target gear is formed. Furthermore, when the driver releases the accelerator pedal 105, the TMECU 200 selects a gear shift stage to obtain a deceleration corresponding to the vehicle speed (current vehicle speed) V based on the acceleration of the vehicle 1 detected by an acceleration sensor (not shown) or calculated based on changes in the rotational speed of the output shaft 27 of the transmission 25 and the deceleration in the accelerator-off state that is predetermined for each vehicle speed, and controls the hydraulic control device 28 to achieve that gear shift stage.

The air conditioning device 30 includes a blower 31 that generates an air flow in an air conditioning duct (not shown) for directing conditioned air into the vehicle cabin, a heater core 32 that heats the air circulating in the air conditioning duct mainly when heating the vehicle cabin, and a refrigeration cycle (not shown) that cools the air circulating in the air conditioning duct mainly when cooling the vehicle cabin. The heater core 32 is connected to a circulation passage of the cooling water of the engine 10 via a thermostat valve 33. The cooling water is pumped by a water pump 34 in the circulation passage and supplied to the engine 10, and the cooling water that has absorbed heat from the engine 10 is supplied from the thermostat valve 33 to either the heater core 32 or the radiator 35 depending on the temperature Tw of the cooling water. As a result, the heater core 32 heats the air in the air conditioning duct (air from the evaporator side of the refrigeration cycle) using the cooling water from the engine 10 supplied via the thermostat valve 33 as a heat source.

The air conditioning ECU 300 includes a microcomputer having a CPU, ROM, RAM, input/output interface, etc., and exchanges information with the engine ECU 100. The air conditioning ECU 300 acquires signals from various switches provided on the instrument panel inside the vehicle cabin, the room temperature detected by a vehicle room temperature sensor (not shown), the cooling water temperature Tw detected by the water temperature sensor 101, the outside air temperature Ta detected by the outside air temperature sensor 102, etc., and controls the air conditioning device 30 based on these signals, etc.

In this embodiment, while the vehicle 1 is in a drivable state (READY-ON state), the air conditioning ECU 300 acquires the cooling water temperature Tw and the outside air temperature Ta, which indicate the temperature of the engine 10, at predetermined time intervals (micro time), and derives a temperature corresponding to the outside air temperature Ta by appropriately performing linear interpolation from the map shown in FIG. 2, and sets the fuel cut prohibition request temperature (hereinafter referred to as the "F/C prohibition request temperature") Tfc for determining whether or not fuel cut is required. The map in FIG. 2 was created through experiments and analyses in advance to define the relationship between the outside air temperature Ta and the F/C prohibition request temperature Tfc. The F/C prohibition request temperature Tfc is set for each outside air temperature Ta slightly higher than the lower limit of the cooling water temperature Tw that ensures the heating performance of the air conditioning device 30 even if fuel cut is performed in the engine 10, and is set higher as the outside air temperature Ta decreases, as shown in the figure.

After setting the F/C prohibition request temperature Tfc, the air conditioning ECU 300 compares the cooling water temperature Tw obtained from the water temperature sensor 101 with the F/C prohibition request temperature Tfc. If the air conditioning ECU 300 determines that the cooling water temperature Tw is equal to or lower than the F/C prohibition request temperature Tfc, it determines that it is necessary to prohibit fuel cut in order to ensure the heating performance of the air conditioning device 30, and sends a heating request signal to the engine ECU 100. When the engine ECU 100 receives a heating request signal from the air conditioning ECU 300, it turns on an F/C prohibition request flag, which is normally off, to indicate that a request has been made to prohibit fuel cut.

Here, if fuel cut is uniformly prohibited in response to a request from the air conditioning ECU 300 to prohibit fuel cut, for example, sufficient deceleration cannot be ensured in response to the release of the accelerator pedal 105 while the vehicle 1 is traveling downhill, and the drivability of the vehicle 1 may deteriorate. On the other hand, if the prohibition of fuel cut is restricted to ensure the heating performance of the air conditioning device 30 by prioritizing drivability, for example, the temperature Tw of the engine 10, i.e., the coolant, in which fuel has been cut, may drop while the vehicle 1 is coasting in a low-temperature environment, causing the occupants of the vehicle 1 to feel a decrease in the heating performance of the air conditioning device 30. Based on this, in the vehicle 1 of this embodiment, the engine ECU 100 as a control device executes a fuel cut permission routine illustrated in FIG. 3.

The routine in FIG. 3 is repeatedly executed by the engine ECU 100 at predetermined time intervals (very short time intervals) while the vehicle 1 is in a drivable state (READY-ON state). When starting the routine in FIG. 3, the engine ECU 100 (CPU) acquires information necessary for processing, such as the coolant temperature Tw from the water temperature sensor 101, the outside air temperature Ta from the outside air temperature sensor 102, the vehicle speed (current vehicle speed) V from the vehicle speed sensor 103, the accelerator opening Acc from the accelerator pedal position sensor 104, the current gear Gn of the transmission 25 from the TMECU 200, and the values of various flags including the F/C prohibition request flag (step S100). After the processing in step S100, the engine ECU 100 determines whether the various sensors related to the processing in FIG. 3, including the water temperature sensor 101 and the outside air temperature sensor 102, are normal (step S110).

When it is determined that an abnormality has occurred in at least one of the sensors related to the processing of FIG. 3 (step S110: NO), the engine ECU 100 turns off the fuel cut prohibition flag (step S190) to allow the execution of fuel cut with priority given to the drivability of the vehicle 1, and temporarily ends the routine of FIG. 3. When the fuel cut prohibition flag is turned off in step S190, the engine ECU 100 controls the multiple injectors to stop the supply of fuel to all combustion chambers of the engine 10 in response to the establishment of the above-mentioned fuel cut execution condition.

When it is determined that the various sensors are normal (step S110: YES), the engine ECU 100 derives a temperature corresponding to the outside air temperature Ta obtained in step S100 by appropriately performing linear interpolation from the map shown in FIG. 4, and sets the temperature as the warm-up determination water temperature Tref for determining the warm-up state of the engine 10 (step S120). The map in FIG. 4 was created in advance through experiments and analysis to define the relationship between the outside air temperature Ta and the warm-up determination water temperature Tref. The warm-up determination water temperature Tref corresponds to the minimum temperature when the engine 10 has completed warming up, and is set lower as the outside air temperature Ta decreases, as shown in the figure.

After setting the warm-up judgment water temperature Tref in step S120, the engine ECU 100 judges whether the cooling water temperature Tw (temperature of the engine 10) acquired in step S100 is equal to or higher than the warm-up judgment water temperature Tref (step S130). If the cooling water temperature Tw is lower than the warm-up judgment water temperature Tref and it is judged that the warm-up of the engine 10 is not completed (step S130: NO), the engine ECU 100 turns off the fuel cut prohibition flag (step S190) and temporarily ends the routine in FIG. 3. In other words, before the warm-up of the engine 10 is completed, the cooling water temperature Tw is relatively low and the deterioration in the heating performance of the air conditioning device 30 due to the decrease in the cooling water temperature caused by the fuel cut is relatively small, so that the execution of the fuel cut is permitted with priority given to drivability.

When it is determined that the cooling water temperature Tw is equal to or higher than the warm-up judgment water temperature Tref (step S130: YES), the engine ECU 100 determines whether or not fuel cut is being performed in the engine 10 at that time and whether the driver is depressing the accelerator pedal 105 (step S140). When it is determined that fuel cut is being performed in the engine 10 or the driver is not depressing the accelerator pedal 105 (step S140: NO), the engine ECU 100 turns off the fuel cut prohibition flag (step S190) and temporarily ends the routine in FIG. 3. This makes it possible to prevent the fuel cut from being interrupted during the execution of the fuel cut, which would otherwise cause the deceleration to decrease.

When it is determined that the engine 10 is not cutting fuel and the driver is depressing the accelerator pedal 105 (step S140: YES), the engine ECU 100 determines whether the FC prohibition request flag acquired in step S100 is on, i.e., whether the air conditioning ECU 300 has requested the prohibition of fuel cutting (step S150). When it is determined that the FC prohibition request flag is off (step S150: NO), the engine ECU 100 turns off the fuel cut prohibition flag (step S190) and temporarily ends the routine of FIG. 3.

On the other hand, if the FC prohibition request flag is on and it is determined that the air conditioning ECU 300 has requested the prohibition of fuel cut (step S150: YES), the engine ECU 100 derives the vehicle speed corresponding to the current gear Gn of the transmission 25 acquired in step S100 from the map shown in FIG. 5 and sets the vehicle speed as the fuel cut prohibition permission lower limit vehicle speed (hereinafter simply referred to as the "lower limit vehicle speed") Vfc (step S160). The map in FIG. 6 was created in advance through experiments and analysis to define the lower limit vehicle speed Vfc for each gear of the transmission 25. The lower limit vehicle speed Vfc corresponds to the lower limit value of the vehicle speed that makes it possible to secure the deceleration required when the accelerator pedal 105 is released by changing the gear ratio, i.e., by downshifting, and is set higher as the gear shifts to the higher speed side (as the gear ratio becomes smaller).

After setting the lower limit vehicle speed Vfc in step S160, the engine ECU 100 determines whether the vehicle speed V acquired in step S100 is equal to or higher than the lower limit vehicle speed Vfc (step S170). If it is determined that the vehicle speed V is equal to or higher than the lower limit vehicle speed Vfc (step S170: YES), the engine ECU 100 turns on the fuel cut prohibition flag (step S180) to prohibit the execution of the fuel cut in order to prioritize the heating performance of the air conditioning device 30, and temporarily ends the routine of FIG. 3. If the fuel cut prohibition flag is turned on in step S180, fuel is continuously supplied to all combustion chambers of the engine 10 even if the fuel cut execution condition is established. At this time, the engine ECU 100 controls the throttle valve so that the intake air amount becomes a predetermined minimum intake air amount, and controls the multiple injectors so as to inject an amount of fuel according to the minimum intake air amount. As a result, the engine 10 rotates at a speed (e.g., idle speed) that corresponds to the minimum intake air volume without outputting a driving force (torque) that exceeds the running resistance.

On the other hand, if it is determined that the vehicle speed V is less than the lower limit vehicle speed Vfc (step S170: NO), the engine ECU 100 turns off the fuel cut prohibition flag (step S190) and temporarily ends the routine in FIG. 3. As a result, even if the air conditioning ECU 300 has requested the prohibition of fuel cut, if the vehicle speed V is less than the lower limit vehicle speed Vfc corresponding to the current gear position Gn of the transmission 25, the engine ECU 100 controls the multiple injectors to stop the supply of fuel to all combustion chambers of the engine 10 in response to the establishment of the fuel cut execution condition.

As described above, the vehicle 1 includes the engine 10, the transmission 25, and the air conditioning device 30 that uses the engine 10 as a heat source, and is controlled by the engine ECU 100 and the air conditioning ECU 300 as control devices. In addition, the air conditioning ECU 300 as a fuel cut prohibition request unit requests the prohibition of fuel cut to ensure the heating performance of the air conditioning device 30 when the cooling water temperature Tw indicating the temperature of the engine 10 is equal to or lower than the F/C prohibition request temperature Tfc corresponding to the outside air temperature Ta. Furthermore, the engine ECU 100 as a fuel cut permission/non-permission determination unit acquires the lower limit vehicle speed Vfc that allows the prohibition of fuel cut corresponding to the current gear stage (current gear ratio) Gn of the transmission 25 in response to the request for prohibition of fuel cut by the air conditioning ECU 300 (steps S150, S160). Then, if the vehicle speed V is equal to or greater than the lower limit vehicle speed Vfc (step S170: YES), the engine ECU 100 prohibits fuel cut (step S180), and if the vehicle speed V is less than the lower limit vehicle speed Vfc (step S170: NO), the engine ECU 100 permits fuel cut (step S190).

As a result, when the air conditioning ECU 300 requests the prohibition of fuel cut and the vehicle speed V is equal to or higher than the lower limit vehicle speed Vfc, fuel cut is not performed even if the fuel cut execution condition is satisfied, so that the heating performance of the air conditioning device 30 can be secured well. Also, in this case, since the vehicle speed V of the vehicle 1 is relatively high, it is possible to secure sufficient deceleration in response to the release of the accelerator pedal 105 by downshifting the transmission 25 to change the gear ratio to the deceleration side. On the other hand, when the air conditioning ECU 300 requests the prohibition of fuel cut and the vehicle speed V is less than the lower limit vehicle speed Vfc, fuel cut is executed in response to the satisfaction of the fuel cut execution condition. As a result, although the heating performance of the air conditioning device 30 may be slightly reduced, sufficient deceleration in response to the release of the accelerator pedal 105 can be secured by fuel cut. As a result, in the vehicle 1, it is possible to further improve drivability while suppressing the deterioration of the heating performance of the air conditioning device 30.

In addition, in the vehicle 1, the lower limit vehicle speed Vfc is determined in advance for each gear (gear ratio) of the transmission 25 as the lower limit vehicle speed at which the deceleration required when the accelerator pedal 105 is released can be secured by downshifting (changing the gear ratio), and is set higher as the gear shifts to the higher speed side (as the gear ratio becomes smaller) (see FIG. 5). This makes it possible to further improve the drivability of the vehicle 1 while appropriately securing the region in which prohibiting fuel cut is permitted and suppressing a decrease in the heating performance of the air conditioning device 30.

Furthermore, in the vehicle 1, the F/C prohibition request temperature Tfc is set higher as the outside air temperature Ta decreases (see FIG. 2). This makes it possible to appropriately request the prohibition of fuel cut to ensure the heating performance of the air conditioning device 30. Furthermore, in the vehicle 1, the engine ECU 100 permits fuel cut (step S190) before the engine 10 has finished warming up (step S130: NO), regardless of the request for prohibition of fuel cut by the air conditioning ECU 300. Furthermore, after the engine 10 has finished warming up, the engine ECU 100 compares the vehicle speed V with the lower limit vehicle speed Vfc in response to the request for prohibition of fuel cut by the air conditioning ECU 300 (steps S150-S170). This makes it possible to effectively prevent the occupants of the vehicle 1 from feeling a decrease in the heating performance of the air conditioning device 30.

As described above, the vehicle control device disclosed herein includes an internal combustion engine (10), a transmission (25) that transmits power from the internal combustion engine (10) to the drive wheels (DW), and an air conditioning device (30) that conditions the air inside the vehicle cabin using the internal combustion engine (10) as a heat source, and controls a vehicle (1) in which a fuel cut is performed by the internal combustion engine (10) in response to the establishment of a fuel cut execution condition, including the release of the accelerator pedal (105). Furthermore, the control device includes a fuel cut prohibition request unit (300) that requests the prohibition of fuel cut when the temperature (Tw) of the internal combustion engine (10) is equal to or lower than a predetermined fuel cut prohibition request temperature (Tfc), and a fuel cut permission/prohibition determination unit (100) that obtains a lower limit vehicle speed (Vfc) that permits the prohibition of fuel cut corresponding to the current gear ratio (Gn) of the transmission (25) in response to a request for prohibition of fuel cut by the fuel cut prohibition request unit (300), prohibits fuel cut when the vehicle speed (V) is equal to or higher than the lower limit vehicle speed (Vfc), and permits fuel cut when the vehicle speed (V) is lower than the lower limit vehicle speed (Vfc). This makes it possible to further improve the drivability of the vehicle while suppressing a decrease in the heating performance of the air conditioning device.

In the vehicle 1, the air conditioning ECU 300 functions as a fuel cut prohibition request unit that requests the prohibition of fuel cut according to the temperature (cooling water temperature Tw) of the engine 10, but is not limited to this. That is, the setting of the F/C prohibition request temperature Tfc and the comparison process between the cooling water temperature Tw and the F/C prohibition request temperature Tfc may be executed by the engine ECU 100, or may be executed by both the air conditioning ECU 300 and the engine ECU 100. In addition, the fuel cut execution condition may be for suppressing deterioration of the catalyst or for regenerating the particulate filter. Furthermore, the transmission 25 is not limited to the stepped transmission as described above, but may be a mechanical continuously variable transmission such as a belt-type continuously variable transmission, or may be an electric continuously variable transmission including, for example, two motor generators (and planetary gears). When such a continuously variable transmission is used as the transmission 25, the lower limit vehicle speed Vfc may be assigned to each of a plurality of predetermined ranges of gear ratios instead of the gear stages of the stepped transmission. Furthermore, the transmission 25 may include an electric continuously variable transmission and a mechanical transmission connected to the output shaft of the electric continuously variable transmission. In this case, the lower limit vehicle speed Vfc may be determined for the electric continuously variable transmission of the transmission 25, or may be determined for the mechanical transmission.

The invention disclosed herein is in no way limited to the above embodiment, and it goes without saying that various modifications can be made within the scope of the present disclosure. Furthermore, the above embodiment is merely one specific form of the invention described in the Summary of the Invention section, and does not limit the elements of the invention described in the Summary of the Invention section.

The disclosed invention can be used in the vehicle manufacturing industry, which includes an internal combustion engine, a transmission, and an air conditioning system that uses the internal combustion engine as a heat source to condition the air inside the vehicle.

1 vehicle, 10 engine, 11 crankshaft, 20 power transmission device, 21 torque converter, 22 lock-up clutch, 23 damper mechanism, 24 mechanical oil pump, 25 transmission, 26 input shaft, 27 output shaft, 28 hydraulic control device, 29 differential gear, 30 air conditioning device, 31 blower, 32 heater core, 33 thermostat valve, 34 water pump, 35 radiator, 100 engine electronic control device (engine ECU), 101 water temperature sensor, 102 outside air temperature sensor, 103 vehicle speed sensor, 104 accelerator pedal position sensor, 105 accelerator pedal, 200 transmission electronic control device (TMECU), 300 air conditioning electronic control device (air conditioning ECU), DS drive shaft, DW drive wheels.

Claims (1)

A control device for a vehicle including an internal combustion engine, a transmission that transmits power from the internal combustion engine to drive wheels, and an air conditioning device that conditions air inside a vehicle cabin using the internal combustion engine as a heat source, wherein a fuel cut is performed in the internal combustion engine in response to establishment of a fuel cut execution condition, including release of an accelerator pedal,
a fuel cut prohibition request unit that requests prohibition of the fuel cut when a temperature of the internal combustion engine is equal to or lower than a predetermined fuel cut prohibition request temperature;
a fuel cut permission/prohibition determination unit that, in response to a request for prohibition of the fuel cut by the fuel cut prohibition request unit, obtains a lower limit vehicle speed that permits prohibition of the fuel cut corresponding to a current gear ratio of the transmission, and prohibits the fuel cut when the vehicle speed is equal to or higher than the lower limit vehicle speed, and permits the fuel cut when the vehicle speed is lower than the lower limit vehicle speed;
Equipped with
the fuel cut prohibition request temperature is set for each outside air temperature higher than a lower limit value of a coolant temperature that allows the heating performance of the air conditioner to be ensured even if a fuel cut is executed in the internal combustion engine, and is set higher as the outside air temperature decreases;
A vehicle control device in which the lower limit vehicle speed is determined for each gear stage of the transmission as a lower limit value of the vehicle speed that enables the deceleration required when the accelerator pedal is released to be secured by downshifting, and is set higher as the gear stage shifts to a higher speed .

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